祁连山森林草原带坡面尺度土壤有机碳分布

以祁连山森林草原带3个山头为研究对象,在坡面尺度上分析了坡向和坡位对不同深度(0~10、10~20、20~40、40~60 cm)土壤有机碳浓度和密度的影响。结果表明:坡肩、背坡及坡脚各层有机碳浓度变化趋势为北坡>西坡>西南坡>南坡,不同沟谷土壤有机碳浓度差异不显著。有机碳浓度的坡位分布因坡向而异,在南坡、西南坡及西坡,沟谷各层有机碳浓度均显著高于其他坡位(P<0.05),坡脚高于坡肩与背坡;在北坡,坡肩、背坡及坡脚有机碳浓度无显著差异,沟谷20~40、40~60 cm土层有机碳浓度显著低于坡肩(P<0.05)。不同层次土壤有机碳密度的变化特征与有机碳浓度相似,0~60 cm有机碳密度最大值出现在北坡(33.64±0.91 kg·m^-2)及沟谷(34.30±2.55 kg·m^-2),约为南坡的3.20倍,西南坡的2.87倍、西坡的1.90倍。

Distribution of Soil Organic Carbon at Hillslope Scale in Forest-steppe Zone of Qilian Mountains

This study examined the effect of slope aspects and positions on SOC concentration and density of different soil depths (0-10, 10-20, 10-20, 20-40,40-60 cm) in forest-steppe zone of Qilian Mountains. Results showed that SOC concentration of whole soil profile increased continuously from south, southwest, west to north-facing slopes at shoulderslope, backslope and footslope positions, while no significant differences were found among valleys. The distribution pattern of SOC concentration among slope positions varied with slope aspects. On south, southwest, and west-facing slopes, SOC concentration at valleys was significantly higher than other slope positions (P<0.05), and footslope position tended to be higher than shoulderslope and backslope positions. On north-facing slope, there was no significant difference among shoulderslope, backslope and footslope positions, and SOC concentration at 20-40 cm and 40-60 cm depths of valley was significantly lower than shoulderslope position (P<0.05). The distribution pattern of SOC density was similar to concentration. SOC density at 0-60 cm depth was maximal on north-facing slope (33.64±0.91 kg·m^-2) and valley (34.30±2.55 kg·m^-2), and was significantly larger than south, southwest and west-facing slopes by factors of 3.20, 2.87 and 1.90, respectively.